OHS W4

Root Morphology

Anatomical root

-area of root below CEJ

-covered by cementum

Apex

end of root

Periapical foramen

opening of apex where blood vessels and nerves enter pulp canal

Which teeth have 1 root?

-Incisors, Canines

-Mandibular 1st premolar (rarely bifurcated)

-Mandibular 2nd premolar (never bifurcated)

Which teeth have 2 roots

-Mandibular molars

-maxillary 1st premolar (commonly bifurcated)

-maxillary 2nd premolar (occasionally bifurcated)

Which teeth have 3 roots?

maxillary molars

Root trunk

the area of bifurcated/trifurcated roots that are unbranched

The root trunk on the max pre-molar is…

far bifurcated and shortest

Sensory system

warns tooth of threats

Support system

anchorage (more spread out roots, stronger)

Functions of the roots

1. Sensory system

2. support system

3. external and internal reparative methods

4. houses the pulp tissue

External and internal reparative methods

responds to pathology, pressure, trauma or movement

Houses the pulp tissue

Nerves and nourishment

Dentin tubules

tiny tubules leading to and from the sensitive pulp (containing nerves and blood vessels)

responsible for feeling pain

What is the only response a nerve of pulp/root canal can emit once stimulated?

Pain

Exposed dentin can..

easily stimulate the nerve through the tubules

What 2 factors are elicited from nerves in bone, gingiva and PDL?

Pressure and temperature

What could cause the root to be exposed?

Periodontal disease, recession, trauma, pathology

The pulp becomes inflamed and damaged in response to ..

trauma

(external/internal ex. infection)

What is the best predictor of loss of vitality?

Cold

What happens during a pain response to heat?

The gases expand causing pressure on the nerves.

The gases are forced out from apical foramen, pain from nerves in bone gingiva, periodontal ligament.

What happens during a pain response to cold?

pain = nerve alive but badly inflamed

no pain = necrotic(dead tooth)/non-vital

Periodontal ligaments

support structure found between the cementum on the root and the alveolar bone

collagenous fibers of connective tissue capable of being tensed (pulled) or compressed

if the PDL is like a hammock, are teeth embedded in bone?

no, the tooth is supported between the root and the alveolar bone by the PDL.

What are some other root characteristics that aid in supporting the tooth?

1. width of roots (more anchorage)

2. shape of roots

3. length of root

4. number of roots

5. concavities (have more room for PDL fibers)

6. direction of the PDL fibers

Would a multi-rooted tooth have more or less resistance to movement and displacement than a single rooted tooth?

More resistance because the PDL’s are dispersed in many more directions than a single rooted tooth

Roots with triangular cross section offer resistance to…

lateral displacement

Curved roots offer resistance to…

lateral, occlusal, apical

PDL in furcation allow resistance to…

occlusal displacement

Apical foramen functions

-allow nutrients and oxygen to circulate throughout the pulp

-provide a system to remove harmful products and carbon dioxide from the totoh

What happens to the nerves and other tissues inside the pulp chamber if the flow of these vessels is restricted?

the neve tissues die from lack of oxygen (anoxia)

Odontoblasts are responsible for….

the formation of secondary and reparative dentin (build) in response to trauma

Cementoma

a benign (harmless) tumor that grows from the cementum that covers the roots

Hypercementosis

Extreme process of cementum formation on outside of root

Mobility

the movement of teeth

Osteoclasts

cells that destroy bone, dissolve bpne in the area of the pressure

Tension on the other side of the tooth stimulates what?

Osteoblasts to form bone (build)

What is the result of residual tension of PDL?

causes tooth to move back and relapse phenomenon

General characteristics of roots

basically cone-shaped, being widest at CEJ and converging to apex

Root inclination of maxillary roots (facial view)

all incline inwards

Root inclination of mandibular roots (facial view)

Anteriors tilt inward

Premolars are more vertical

Molars tilt outwards

Dilaceration

unexpected root curvature

Enamel pearls

small elevations of enamel on root surface-usually in furcation